Magnetic junk retriever



Dec. 5, 1961 M. D. MOSELEY, JR

MAGNETIC JUNK RETRIEVER Filed Dec. 12, 1958 INVENTOR Meek/e 0. Mose/ex. BY

ATTORNEYS United States Patent MAGNETIC JUNK RETRIEVER Meekie D. Moseley, In, Tyler, Tex.

(515 Garland Ave., Beaumont, Tex.)

Filed Dec. 12, 1958, Ser. No. 779,893 7 Claims. (Cl. 294-655) V This invention relates to new and useful improvements in magnetic junk retrievers.

One object of the invention is to provide an improved junk retriever which is arranged to magnetize a drill bit whereby pieces of ferrous metal that have broken off and fallen to the bottom of a well bore are attracted and cling to the bit for removal therewith.

-Another object of the invention is to provide an improved magnetic junk retriever which includes a tool having a magnet and adapted to pass downwardly through a drill pipe into engagement with its bit for magnetizing the bit to cause ferrous metal junk to cling thereto whereby the junk is retrieved upon withdrawal of said bit so as to make it unnecessary to fish for said junk in a separate'operation before substituting a new bit.

A further object of the invention is to provide an improved magnetic junk retrieving tool, of the character described, which is capable of being dropped or pumped downwardly through a drill pipe whereby the drill bit may be magnetized whenever desired to permit the retrieving of junk so as to save time and'expense.

A construction designed to carry out the invention will be hereinafter described, together with other features of the invention.

The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawing, wherein examples of the invention are shown, and wherein:

HG. l is alongitudinal, sectional view of a drill pipe and bit in a well bore with the bit engaged by a magnetic junk retrieving tool constructed in accordance with the invention,

FIG. 2 is a longitudinal, sectional view of the tool,

FIG. 3 is a longitudinal, sectional view of the upper portion of a modified tool, and

FIG. 4 is an enlarged, plan view of the seat at the upper end of the drill bit for engagement by the lower end of the tool.

In the drawing, the numeral designates a well bore which may be drilled by a rotary bit 11 mounted on the lower end of a drill stem or pipe 12. A sub 13, having a relatively thick wall, connects the bit 11 to the stem 12 and said bit has an upstanding, tubular shank 14 for screw-threaded engagement with the sub. Ports or passages 15 depend from the bore of the shank 14 to conduct drilling fluid from the stem to the cutting elements or teeth 16 of the drill bit. The sub 13 is formed of monel or other suitable non-ferromagnetic material to insulate the bit from the stem, both of which are of steel. Since the bit is subject to wear and breakage, it is necessary to replace said bit from time to time. The broken parts of the bit, such as teeth and bearings, as well as other pieces of ferrous metal or junk fall to the bottom of the well bore 10 and become embedded.

therein. Heretofore, in order to protect the new bits from damage or premature wear, a magnetic or other fishing tool has been mounted on the drill stem and lowered into the well bore in place of the removed bit to retrieve the ferrous metal pieces or junk. The drill stem is required to provide circulation of drilling fluid and I0- tation of the tool for dislodging the embedded junk.

This time-consuming and expensive retrieving operation has been eliminated by the provision of an improved device or tool 17 for magnetizing the drill bit 11,

bit for removal therewith from the well bore. The tool' whereby the ferrous junk is attracted and clings to said 17 is in the form of an elongated, hollow body or cylindrical housing and includes a tubular casing or sleeve 18 of stainless steel or other suitable material which is substantially non-ferromagnetic. Preferably, the body is sectional and has a relatively short sleeve or extension 19 screwthreaded to the upper end of its sleeve 18 (FIG. 2). A fishing neck 20 is sc'rewthreaded to the upper end of the sleeve 19 and is of the usual construction for detachable connection with a wire line or cable (not shown). The lower end of the sleeve 18 is screwthreaded in an annular flange or collar 21 upstanding from a cylindrical, solid portion or head 22, of mild steel or other ferromagnetic metal, having an axial, screwthreaded recess or socket 23 below its collar. For engagement with the drill bit, a replaceable portion or nose 24 may be 'screwthreaded on the lower end of the head 22 and has a flat bottom or lower end which is bevelled or chamfered. at 'its margin 25. With the exception of the reduced upper end' portion of the fishing neck 20, the tool 17 isofthe same diameter throughout its length and of-slightly less diameter than the bore of the drill stem 12 to permit the flow of fluid between said bore andtool.. External, longitudinal channels or grooves 26 may be formed in the head 22 and nose 24 to insure communicationbetween the bore of the stem and the fluid passages 15 of the bit.

For magnetizing the drill bit so as to attract ferrous junk thereto, a magnet 27 is mounted in the tool 17 and includes an electromagnetic winding or coil 28 extending longitudinally of and substantially coextensive with the sleeve 18 in spaced relation thereto and surrounding an axial core 29 of mild steel or other ferromagnetic metal. The lower end of the coil 28 is supported by an angular ring or retainer 30 which encircles and which is suitably secured to the core 29. As shown by the numeral 31, the lower end of the core projects beyond the coil and is screwthreaded for engagement in the socket 23 of the head 22 whereby said head forms an extension of said core. A circular disk or plate 32 overlies the flush upper ends of the coil and core,Tbeing fastened to the core by suitable screws 33. Above the plate 32 and below the sleeve 19, a spider 34 is screwthreaded in the upper end of the sleeve 18 and is attached to said plate by fasteners 35. One end of the coil is connected to the spider 34' by a lead wire 36, while a lead wire 37 connects the other end ofsaid coil to an axial contact element or terminal 38 overlying and supported by said spider. As shown by the'numeral 39, the lead wire 37 andcontact element 38'are suitably insulated from the spider and the contact element is engaged by the terminal 40 of an overlying source of current or mercury cell 41 mounted in the sleeve 19. A substantially helical spring 42 is confined between the fishing neck 20 and mercury cell 41 for urging the cell downwardly to maintain its terminal 40 in engagement with the contact element.

Although the nose 24 of the head 22 may seat in the bore of the drill bit shank 14, it is desirable to provide a complementary, annular seat or shoulder 45 of ferromagnetic metal for engagement by said nose. As shown most clearly in FIG. 4, the seat 45 is in the form of a ring of substantially the same external diameter as the shank and confined between said shank and the sub 13. An annular, bevelled or chamferred surface or seat 46, complementary to the bevelled or chamferred margin 25, of the nose, is formed in the upper surface of the ring and said nose is adapted to rest therein. Externally of its surface 46, the ring has a plurality of ports or passages 47 extending axially therethrough to permit the flow of fluid around the seated head and its nose. Manifestly, the ring 45 provides a positive contact or engagement between the bit and tool and functions as a part of said bit.

When it is desired to retrieve ferrous junk from the well bore 10, the tool 17 is dropped or pumped downwardly through the drill stem 12. Although the tool may be lowered by its fishing neck 20, it is noted that said neck is provided to permit withdrawal of said tool from the drill stem whenever desirable or necessary. Due to the bevelled margin 25 of the nose 24, the tool is prevented from hanging on the joints of the stem. It is pointed out that the combined length of the ferromagnetic head 22- and its nose is less than the length of the non-ferromagnetic sub 13 so that the upper end of said head terminates below and is spaced from the lower end of the stem when the nose rests on the seat 45. As a result, the force of the'magnet 27 is directed downwardly to the drill bit 11 through the seat by the head and its nose and is not transmitted to the stern. Due to the magnetizing of the bit, the ferrous junk is attracted and clings to said bit for removal therewith from the well bore.

The dislodging of junk embedded in the bottom of the well bore is facilitated by rotation of the bit and the circulation of drilling fluid around the seated tool to the passages 15, it being noted that the ports 47 of the seat provide constant communication between said passages and the bore of the drill stem. Due to the fact that replacement of the bit necessitates withdrawal of the drill stem, it is extremely advantageous to retrieve the ferrous junk immediately prior to such withdrawal by using the tool 17 to magnetizethe drill bit. The time and expense of a complete round trip of the stem are eliminated, since it is unnecessary to use said stem for lowering and separately removing the tool 17. As shown in FIG. 3, additional mercury cells 43 may be employed and may be mounted in extensions or sleeves 44 interposed between the sleeves 18 and 19.

The aforegoing description of the invention is explanatory thereof and various changes in the size, shape and materials, as well as in the details of the illustrated construction may be made, within the scope of thevappended claims, without departing from the spirit of the invention.

What I claim and desire to secure by Letters Patent is:

1. A magnetic junk retrieving tool for magnetizing a drill bit on the lower end of a drill pipe and magnetically insulated therefrom including an elongated body adapted to be lowered through the drill pipe, a head of ferromagnetic material at the lower end of the body for seating engagement with the drill bit, said body having a hollow portion above the head, and a magnet in the hollow portion of said body and engaging said head to magnetize the drill bit and attract ferrous junk to the bit for removal therewith from a well bore, said body being supported by and removed with the bit.

2. A magnetic junk retrieving tool as set forth in claim 1 including a seat at the upper end of the drill bit for engagement by the lower end of the head.

3. A magnetic junk retrieving tool for magnetizing a drill bit on the lower end of a drill pipe and magnetically insulated therefrom including an elongated body adapted to be lowered through the drill pipe, a head of ferromagentic material at the lower end of the body 'for seating engagement with the drill bit, said body having a hollow portion above the head, an electromagnet in the hollow portion of said body and having connection with said head, and a source of current for the electromagnet in said hollow portion, whereby ferrous junk is attracted and clings to the drill bit for removal therewith from a well bore when the bit is engaged by said head, said body being supported by and removed with the bit.

4. A magnetic junk retrieving tool as set forth in claim 3 wherein the electromagnet-includes' an axial core connected to the head, and a coil surrounding the core and having connection with the source of current.

5. In combination with a drill bit connected to a drill:

pipe by a sub of non-ferromagnetic material, a magnetic junk retrieving tool including an elongated cylindrical body adapted to be lowered through the drill pipe, a head of ferromagnetic material at the lower end of the body for seating engagement with the drill bit, the head terminating below the upper end of the sub when engaged with the bit, said body having a tubular portion above said head, and a magnet in the tubular portion and engaging said head for magnetizing the bit where by ferrous junk is attracted and clings to the bit for removal therewith from a well bore, said body being supported by and removed with the bit.

6. The combination set forth in claim 5 including a seat of ferromagentic metal at the upper end of the drill bit for engagement by the head.

7. In combination with a drill bit connected by a sub of non-ferromagnetic material to a drill pipe, a tool for retrieving ferrous junk from the bottom of the well bore including an elongated cylindrical body of less diameter said body being supported by and removed with the bit.

References Cited in the file of this patent UNITED STATES PATENTS 2,451,231 Manegold Oct. 12, 1948 2,493,992 Murphy et a1. Jan. 10, 1950 2,637,590 Ortlofi May 5, 1953 2,657,752 Ballew et al Nov. 3, 1953 

